1. Field of the Invention
The present invention relates to an adhesive applying apparatus for applying an adhesive for fixing an electronic component onto a circuit board.
2. Description of Related Art
A prior art adhesive applying apparatus will be described with reference to FIG. 6 and FIG. 7.
In FIG. 6, a reference character A denotes a perspective view of a prior art adhesive applying apparatus. The reference character B denotes an applying mechanism provided with applying nozzles 1 for applying an adhesive 3, a syringe 2 for supplying the adhesive 3 to the applying nozzles 1 and a monitor camera 13. The reference character C denotes a purging (discard) station mechanism provided with a purging tape 5 for purging the adhesive 3 and a purging station 6 which is located beside a circuit board conveyance unit 10 and places thereon the purging tape 5 in a purging stage. The aforementioned circuit board conveyance unit 10 and the purging station 6 are supported on an X-Y table 30. The circuit board conveyance unit 10 is constructed so as to be able to position the applying nozzle 1 in an X-Y direction.
An adhesive applying operation of the purging station to be executed by the prior art adhesive applying apparatus A prior to shipment from the factory will be described next with reference to FIG. 6 and FIG. 7.
Conventionally, when shipping an adhesive applying apparatus, an operator performs an adjustment for making the height of the upper surface of the purging tape 5 coincide with the height of the upper surface of a circuit board 4 conveyed by the circuit board conveyance unit 10 prior to shipment from the factory. This adjustment is performed by positioning the applying nozzle 1 above the purging station 6, moving the nozzle downward to a preset height corresponding to the upper surface of the aforementioned circuit board 4, loosening screws by which the purging station 6 is mounted so that the tip of the applying nozzle 1 is positioned in contact with the upper surface of the purging tape 5 on the purging station 6 within a stroke in which the board 4 and the nozzle 1 are in contact with each other as shown in FIG. 7, thereby vertically adjusting the position of the purging station 6.
However, in the aforementioned prior art construction, the adjustment of the height position of the purging station 6 and the circuit board 4 has required a significant amount of time. Furthermore, if the height of the upper surface of the purging tape 5 does not coincide with the height of the upper surface of the circuit board 4, conveyed by the circuit board conveyance unit 10, a problem occurs in that the appropriate purging cannot be performed because the tip of the applying nozzle 1 is separated from the upper surface of the purging tape 5 or the tip of the applying nozzle 1 collides with the purging station 6 via the purging tape 5.
The present invention has as an object to provide an adhesive applying apparatus which is capable of easily and speedily adjusting the vertical positional relationship between the upper surface of the circuit board and the upper surface of the purging station during the adjustment stage prior to shipment from the factory or when changing the type of circuit board.
In order to solve the aforementioned problems, the present invention is constructed as follows.
According to a first aspect of the present invention, there is provided an adhesive applying apparatus comprising an adhesive applying nozzle, and an elevation drive unit which moves the adhesive applying nozzle up and down and is able to set a lowermost end position of the adhesive applying nozzle.
The adhesive applying apparatus also includes a purging station provided with a purging tape placed on its upper surface, a support unit (10) for supporting a circuit board to be applied with an adhesive from the adhesive applying nozzle, and a transverse drive unit.
The adhesive applying nozzle is moved relative to the circuit board and the purging tape by the transverse drive unit so as to position the nozzle in a specified position in a transverse direction which is perpendicular to a vertical direction.
A control means is provided for controlling the elevation drive unit via a command to set the lowermost end position of the adhesive applying nozzle, located in a position above the purging station, to a specified position.
According to the present invention, the lowermost end position of the applying nozzle can be appropriately set in the position of the upper surface of the circuit board and in the position of the upper surface of the purging tape placed on the purging station. Therefore, the adhesive can be appropriately applied even when the upper surface of the circuit board does not coincide with the upper surface of the purging station.
According to a second aspect of the present invention, there is provided an adhesive applying apparatus based on the first aspect, wherein the elevation drive unit moves the adhesive applying nozzle down to the lowermost end position according to a thickness of the circuit board upon receiving a command from the control means for setting the lowermost end position of the adhesive applying nozzle to a height of the circuit board.
According to a third aspect of the present invention, there is provided an adhesive applying apparatus based on the first or second aspect, wherein the elevation drive unit is provided with a cam having a curved cam surface, a motor for rotating the cam, a cam follower which moves on the cam surface of the cam, and a shaft which is connected to the nozzle and moves up and down when the cam follower moves on the cam surface of the cam. The motor rotates in accordance with a command from the control means, consequently rotating the cam, moving the cam follower on the cam surface of the cam, moving the shaft in a downward direction and moving the adhesive applying nozzle down to the set lowermost end position.
According to a fourth aspect of the present invention, there is provided an adhesive applying apparatus based on the third aspect, wherein the cam has two cam surfaces of different curvatures so that the lowermost end position of the adhesive applying nozzle varies when the cam follower is moved on the two cam surfaces due to rotation of the motor.
According to a fifth aspect of the present invention, there is provided an adhesive applying apparatus comprising an adhesive applying nozzle, an elevation drive unit for moving the adhesive applying nozzle up and down, a purging station provided with a purging tape placed on its upper surface, and a support unit for supporting a circuit board to be applied with an adhesive from the adhesive applying nozzle.
The apparatus also has a transverse drive unit which moves the adhesive applying nozzle relative to the circuit board and the purging tape so as to position the nozzle in a specified position in a transverse direction perpendicular to a vertical direction.
A station elevation unit is provided for moving the purging station up and down.
Also, a control means is provided for controlling the station elevation unit via a command so as to set a height of the purging station to a specified height.
According to the present invention, the height position of the purging station can be easily and speedily adjusted when a displacement occurs between the position of the upper surface of the circuit board and the position of the upper surface of the purging tape placed on the purging station. Therefore, appropriate purging can be performed.
According to a sixth aspect of the present invention, there is provided an adhesive applying apparatus based on the fifth aspect, wherein the station elevation unit moves the purging station up and down according to a thickness of the circuit board upon receiving the command for setting the height of the purging station to the height of the circuit board from the control means.
According to a seventh aspect of the present invention, there is provided an adhesive applying apparatus based on any of the fourth through sixth aspects. In the seventh aspect, the station elevation unit is provided with a motor and a threaded shaft which is driven by the motor to move the purging station up and down.
According to an eighth aspect of the present invention, there is provided an adhesive applying apparatus based on any of the first through seventh aspects. In the eighth aspect, the circuit board is supported by being positioned by the support unit with its lower surface serving as a reference, and the height of the upper surface of the circuit board is changed every time the thickness of the circuit board is varied.